Galen's On the Elements according to Hippocrates is an important source for physical doctrines circulating in late antiquity. The variety of atomistic doctrines that Galen brings into the discussion, as well as his arguments aimed at refuting them, were closely studied by the early kalām atomists. Of particular interest are the summaries of this text, which seem to have been written many centuries after Galen; some of them are products of early Islamicate culture. In this paper, we present an edition, translation, and study of a hitherto unknown summary, extent in a unique manuscript where it is attributed to Ḥunayn ibn Isḥāq. Like the other summaries, it presents a doxography of physical doctrines, not always repeating precisely what Galen says, but rather reflecting the discourse of its period.